Carbon nanotubes are hollow cylinders of carbon having diameters that are tens of thousands of times smaller than the diameter of a human hair. Carbon nanotubes have high strength and high electrical conductivity, making them useful in many applications. One specific use of carbon nanotubes is as an additive to create electrical conductivity in otherwise electrically insulating plastic materials. Because of health and safety concerns, carbon nanotubes are typically not handled in their pure form when they are used as additives to plastics. Instead, they are typically added to the base plastic as a concentrate or masterbatch in the same plastic or a different plastic. Such carbon nanotube masterbatches in plastic can be safely handled, and they facilitate an even distribution of the carbon nanotubes throughout the final plastic composition. However, the preparation of a carbon nanotube masterbatch in plastic requires a separate high-temperature compounding step that can negatively affect the characteristics and properties of the carbon nanotubes and/or the end product plastic. There is therefore a desire for methods of introducing carbon nanotubes to plastics that do not require a separate high-temperature compounding step. Further desirable would be methods that improve the melt flow of the end product plastic.